How to write a schema to constrain some of the properties with one/any of the sub-schemas?

Can I validate both

name: "range_1"
step: 1
start: 0
stop: 10

and

name: "range_2"
step: 1
center: 5
span: 5

with something like

properties:
    name:
        type: "string"
    stop:
        type: number
    oneOf:
    -   start:
            type: number
        step:
            type: number
    -   center:
            type: number
        span:
            type: number

For now I am using jsonschema in Python, but it complains jsonschema.exceptions.SchemaError: <the array in oneOf> is not of type 'object', 'boolean'.

Validating against name and step only or validating against all possible keys apparently works but they both seem sub-optimal for me.

You need to move the oneOf keyword out of the properties object as everything in the properties object is interpreted as an expected value in your data.

Additionally, it makes sense to add an required property to make the values mandatory. Finally, if you want to make sure that no other values are excepted, you can use additionalProperties: false. Note though, that you have to repeat the "parent" properties in the oneOf schemas again. For further reading I recommend this example.

Put all together, you could use the following schema (see live example here):

---
properties:
  name:
    type: string
  step:
    type: number
oneOf:
- properties:
    name: true
    step: true
    start:
      type: number
    stop:
      type: number
  required:
  - start
  - stop
  additionalProperties: false
- properties:
    name: true
    step: true
    center:
      type: number
    span:
      type: number
  required:
  - center
  - span
  additionalProperties: false